Well, not Hanukah, as that's ended, but Xmas and New Years certainly. The Legion Alpha has been up for a few weeks now, allowing people to play Demon Hunters, get a good portion of the Artifact Weapons (I want to say more than half) quest in Stormheim and Highmountain, and run a couple of dungeons (I believe Halls of Valor and Black Rook Hold are the ones that have been open.)
While it's still officially still an "Alpha," there's a decent amount of the expansion to be open for testing. I suspect that after the holidays things will kick into a higher gear, and it might officially transition over to a Beta.
I don't know exactly what Blizzard considers the distinction between Alpha and Beta, but I'd guess that right now the only people who aren't Blizzard employees or Friends & Family of theirs are probably prominent WoW-journalists, like people at WoWHead, MMO-Champion, and Blizzard Watch. My guess is that the official changeover to "Beta" will mean inviting a wider selection of the playerbase.
There is a new build being pushed to the servers, and I think we might see some data-mining of it even if the Alpha is not officially up. My guess is that we'll see the other "any order" zones, Azsuna and Val'sharah, opening up, as well as perhaps some more dungeons and almost certainly more artifact quests (currently Shamans aren't even playable in the Alpha, so we haven't seen how they get their weapons.)
I also hope that we'll get a much more solid picture of how Vengeance Demon Hunters will work in this build. I'm also pretty excited to get the background on Truthguard (the protection paladin artifact,) and hopefully see some new model variations (right now all the accompanying sword models are just a lot of different color schemes for the same thing.)
I honestly don't really remember the pace of content being opened up in the previous Beta, but what I've seen of the Legion Alpha is pretty promising. We'll of course have to see how they keep up the pace of the rollout, but I think that it's not impossible that we'd get Legion in the first half of 2016 - in fact, I might even go as far as to say that it's more likely than not (knock on wood.)